Three-mode analog controller with remote tuning

Abstract

A three-mode analog controller for regulating a signal corresponding to a controller variable to produce a controller output, comprises an integrating circuit, a proportional circuit, and a derivative circuit. The integrating circuit includes a reset adjustment for varying a time constant thereof, the proportional circuit includes a gain adjustment for varying the gain thereof and the derivative circuit includes a rate adjustment for adjusting the rate of derivation of the signal. The gain adjustment comprises a photoresistor associated with a source of light which is provided with varying current corresponding to the signal to vary the resistance of the photoresistor and, thus, the gain value. The reset and rate adjustments may also comprise photoresistors with light sources or may be formed of field affect transistors each controlled by a circuit and remotely located potentiometer or variable voltage source.

What is claimed is: 
     
       1. A three-mode analog controller for regulating a signal corresponding to a control variable to produce a control output comprising: an integrating circuit for integrating the signal with a selected time constant and having a reset adjustment for varying the time constant;   a proportional circuit for applying a selected gain to the signal and having a gain adjustment for varying the gain; and   a derivative circuit for obtaining a derivative of the signal at a selected rate and having a rate adjustment for varying the rate;   wherein said reset, gain, and rate adjustments comprise a light source, a current line connected between said signal and source for applying a current value to said light source for producing a varied light emission from said light source corresponding to said signal and a photoresistor which varies in resistance with variations in light emitted by said light source.   
     
     
       2. A controller according to claim 1, wherein each of said reset, gain, and rate adjustments comprise a separate light source and separate photoresistor. 
     
     
       3. A controller according to claim 2, including an input terminal for receiving the signal and an output terminal for supplying the control output, a first one of said photoresistors connected to said input terminal, a first capacitor connected in parallel to said first photoresistor, a first operational amplifier connected between said first photoresistor and said output terminal; said derivative circuit comprising a second one of said photoresistors connected to said first operational amplifier input, a second capacitor connected in series with said second photoresistor and a third capacitor connected in parallel with said second photoresistor; said proportional circuit comprising a second operational amplifier having an input connected to said output terminal and an output connected to said second capacitor, a third one of said photoresistors connected between said second capacitor and a ground. 
     
     
       4. A three-mode analog controller for regulating a signal corresponding to a control variable to produce a control output comprising: an integrating circuit for integrating the signal with a selected time constant and having a reset adjustment for varying the time constant;   a proportional circuit for applying a selected gain to the signal and having a gain adjustment for varying the gain;   a derivative circuit for obtaining a derivative of the signal at a selected rate and having a rate adjustment for varying the rate;   wherein each of said integrating and derivative circuits include a field affect transistor and a tuning circuit connected to each field affect transistor for operating each field affect transistor at a selected duty cycle to vary the resistance of each field effect transistor respectively.   
     
     
       5. A controller according to claim 4, wherein each tuning circuit comprises an input terminal for receiving a variable selected voltage value, a first operational amplifier having an input connected to said circuit input and an output, a tuning circuit capacitor connected in parallel with said first operational amplifier, a switching transistor having an emitter collector junction connected across said tuning circuit capacitor, said tuning circuit having an output connected to base of said switching transistor, a second operational amplifier having a first input connected to said first operational amplifier output and a second input adapted to receive a reference voltage, said second operational amplifier acting as a comparator and having an output connected to said tuning circuit output, said tuning circuit output connected to a base of one of said field effect transistors. 
     
     
       6. A controller according to claim 5, including an input terminal for receiving the signal and an output terminal for supplying the controller output, said integrating circuit comprising a first resistor connected to said input terminal and to a first one of said field effect transistors, a first capacitor connected in parallel across said first resistor and first field effect transistor; a third operational amplifier having an input connected to said first field effect transistor and an output connected to said output terminal; said derivative circuit comprising a second resistor connected to said third operational amplifier input and to a second one of said field effect transistors, a second capacitor connected in parallel to said second resistor and second field effect transistor, a third capacitor connected in series with said second capacitor and parallel connected second resistor and second field effect transistor; said proportional circuit comprising a fourth operational amplifier connected between said output terminal and said second capacitor, a potentiometer connected between said second capacitor and a ground. 
     
     
       7. A three-mode analog controller for regulating a signal corresponding to a control variable to produce a control output comprising: an integrating circuit for integrating the signal with a selected time constant and having a reset adjustment for varying the time constant;   a proportional circuit for applying a selected gain to the signal and having a gain adjustment for varying the gain;   a derivative circuit for obtaining a derivative of the signal at a selected rate and having a rate adjustment for varying the rate;   wherein said proportional circuit includes a light source, a current line connected between said signal and source for applying a constant value to said light source for producing a varied light emission from said light source corresponding to said signal and a photoresistor which varies in resistance with variations in light emitted by said light source, each of said integrating and derivative circuits including a field affect transistor and a tuning circuit connected to each field affect transistor for operating each field affect transistor at a selected duty cycle to vary the resistance of each field effect transistor respectively.   
     
     
       8. A controller according to claim 7, wherein each tuning circuit comprises an input terminal for receiving a variable selected voltage value, a first operational amplifier having an input connected to said circuit input and an output, a tuning circuit capacitor connected in parallel with said first operational amplifier, a switching transistor having an emitter collector junction connected across said tuning circuit capacitor, said tuning circuit having an output connected to base of said switching transistor, a second operational amplifier having a first input connected to said first operational amplifier output and a second input adapted to receive a reference voltage, said second operational amplifier acting as a comparator and having an output connected to said tuning circuit output, said tuning circuit output connected to a base of one of said field effect transistors. 
     
     
       9. A controller according to claim 8, including an input terminal for receiving the signal and an output terminal for supplying the controller output, said integrating circuit comprising a first resistor connected to said input terminal and to a first one of said field effect transistors, a first capacitor connected in parallel across said first resistor and first field effect transistor; a third operational amplifier having an input connected to said first field effect transistor and an output connected to said output terminal; said derivative circuit comprising a second resistor connected to said third operational amplifier input and to a second one of said field effect transistors, a second capacitor connected in parallel to said second resistor and second field effect transistor, a third capacitor connected in series with said second capacitor and parallel connected second resistor and second field effect transistor; said proportional circuit comprising a fourth operational amplifier connected between said output terminal and said second capacitor, said photoresistor connected between said second capacitor and a ground.